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Yard and Garden: Get the Most from Your Home Potato Growing Experience

Potatoes are versatile plants and can be used in many ways when grown in the home garden. There’s a lot to know about how to grow and store them properly, however. Here are some tips from Iowa State University Extension and Outreach on ways to maximize the potato experience, with help from ISU Extension and Outreach horticulturists. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or hortline@iastate.edu.

There are small, round, green objects resembling miniature tomatoes on my potato plants. What are they?

The small, round, green objects are the fruit of the potato plant.

Tomatoes and potatoes belong to the Solanaceae or Nightshade family. Plants within a family share certain morphological characteristics. The flowers on tomatoes and potatoes are similar in appearance. Potato fruit are similar in shape (though much smaller in size) to those on tomatoes.

Most flowers on potato plants dry up and drop from the plant and don’t develop into fruit. The fruit that do develop are relatively small and inconspicuous and often go unnoticed by most gardeners. The cultivar ‘Yukon Gold’ fruits more heavily than most other potato cultivars.

Potato fruit are of no value to gardeners. The small fruit should not be eaten, as they contain a poisonous alkaloid (solanine). The fruit are not useful for planting purposes, as potatoes don’t reproduce true from seed.

When should I harvest potatoes?

Potatoes can be harvested when the tubers are small and immature (“new” potatoes) or when the crop is fully mature.

“New” potatoes are dug when the plants are still green and the tubers are greater than 1 inch in diameter. New potatoes should be used immediately, as they do not store well.

Potatoes grown for storage should be harvested after the vines have died and the crop is mature. To check crop maturity, dig up one or two hills after the plants have died. If the skins on the tubers are thin and rub off easily, the crop is not fully mature. Allow the crop to mature for several more days before harvesting the potatoes. When harvesting potatoes, avoid bruising, skinning or cutting the tubers. Damaged potatoes should be used as soon as possible.

How should I store potatoes?

After harvesting the potatoes, cure the tubers at a temperature of 50 to 60 degrees Fahrenheit and high relative humidity (85 to 90 percent) for two weeks. The curing period allows minor cuts and bruises to heal. Thickening of the skin also occurs during the curing process.

Once cured, store potatoes at a temperature of 40 F and relative humidity of 90 to 95 percent. Store the crop in a dark location, as potatoes turn green when exposed to light. If storage temperatures are above 50 F, the tubers may begin to sprout in two to three months. When stored below 40 F, potatoes develop a sugary, sweet taste. Sugary potatoes can be restored to their natural flavor by placing them at room temperature for a few days prior to use. Do not store potatoes with apples or other fruit. Ripening fruit give off ethylene gas, which promotes sprouting of tubers.